Securities (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Securities
Available-for-sale, Less Than Twelve Months, Estimated Fair Value	$ 92,893	$ 1,478
Available-for-sale, Less Than Twelve Months, Gross Unrealized Losses	(589)	(24)
Available-for-sale, Twelve Months or Longer, Estimated Fair Value	10,756	15,261
Available-for-sale, Twelve Months or Longer, Gross Unrealized Losses	(102)	(291)
Available-for-sale, Total, Estimated Fair Value	103,649	16,739
Available-for-sale, Total, Gross Unrealized Losses	(691)	(315)
Held-to-maturity, Less Than Twelve Months, Estimated Fair Value	413,699	54,594
Held-to-maturity, Less Than Twelve Months, Gross Unrealized Losses	(2,760)	(147)
Held-to-maturity, Twelve Months or Longer, Estimated Fair Value	12,259
Held-to-maturity, Twelve Months or Longer, Gross Unrealized Losses	(196)
Held-to-maturity, Total, Estimated Fair Value	425,958	54,594
Held-to-maturity, Total, Gross Unrealized Losses	(2,956)	(147)
GSE issuance REMICs and CMOs
Securities
Available-for-sale, Less Than Twelve Months, Estimated Fair Value	67,841	360
Available-for-sale, Less Than Twelve Months, Gross Unrealized Losses	(583)	(1)
Available-for-sale, Total, Estimated Fair Value	67,841	360
Available-for-sale, Total, Gross Unrealized Losses	(583)	(1)
Held-to-maturity, Less Than Twelve Months, Estimated Fair Value	413,651	53,347
Held-to-maturity, Less Than Twelve Months, Gross Unrealized Losses	(2,759)	(146)
Held-to-maturity, Twelve Months or Longer, Estimated Fair Value	12,259
Held-to-maturity, Twelve Months or Longer, Gross Unrealized Losses	(196)
Held-to-maturity, Total, Estimated Fair Value	425,910	53,347
Held-to-maturity, Total, Gross Unrealized Losses	(2,955)	(146)
Non-GSE issuance REMICs and CMOs
Securities
Available-for-sale, Less Than Twelve Months, Estimated Fair Value		495
Available-for-sale, Less Than Twelve Months, Gross Unrealized Losses		(21)
Available-for-sale, Twelve Months or Longer, Estimated Fair Value	10,709	15,261
Available-for-sale, Twelve Months or Longer, Gross Unrealized Losses	(86)	(276)
Available-for-sale, Total, Estimated Fair Value	10,709	15,756
Available-for-sale, Total, Gross Unrealized Losses	(86)	(297)
Held-to-maturity, Less Than Twelve Months, Estimated Fair Value		1,247
Held-to-maturity, Less Than Twelve Months, Gross Unrealized Losses		(1)
Held-to-maturity, Total, Estimated Fair Value		1,247
Held-to-maturity, Total, Gross Unrealized Losses		(1)
GSE pass-through certificates
Securities
Available-for-sale, Less Than Twelve Months, Estimated Fair Value	57	623
Available-for-sale, Less Than Twelve Months, Gross Unrealized Losses	(1)	(2)
Available-for-sale, Twelve Months or Longer, Estimated Fair Value	47
Available-for-sale, Twelve Months or Longer, Gross Unrealized Losses	(1)
Available-for-sale, Total, Estimated Fair Value	104	623
Available-for-sale, Total, Gross Unrealized Losses	(2)	(2)
Held-to-maturity, Less Than Twelve Months, Estimated Fair Value	48
Held-to-maturity, Less Than Twelve Months, Gross Unrealized Losses	(1)
Held-to-maturity, Total, Estimated Fair Value	48
Held-to-maturity, Total, Gross Unrealized Losses	(1)
Obligations of GSEs
Securities
Available-for-sale, Less Than Twelve Months, Estimated Fair Value	24,995
Available-for-sale, Less Than Twelve Months, Gross Unrealized Losses	(5)
Available-for-sale, Total, Estimated Fair Value	24,995
Available-for-sale, Total, Gross Unrealized Losses	(5)
Freddie Mac and Fannie Mae stock
Securities
Available-for-sale, Twelve Months or Longer, Gross Unrealized Losses	(15)	(15)
Available-for-sale, Total, Gross Unrealized Losses	$ (15)	$ (15)